Keywords: Nitrogen donor ligands / Guanidine ligands / Ligand designA series of bis-guanidine ligands designed for use in biomimetic coordination chemistry has been extended to a library matrix combining unprecedented substitutional flexibility within the guanidyl residues with a wide range of aliphatic and aromatic spacers connecting these functionalities. The underlying protocol can be used with predefined ureas as well as secondary amines to build up these units by reaction with phosgene if the ureas are otherwise unavailable. In the latter case, the resulting urea intermediates do not have to be isolated as the reaction proceeds further with additional phosgene to yield a chloroformamidinium chloride which is transformed into the bis-guanidine functionality by subsequent reaction with a suitable primary diamine in the presence of triethylamine as an auxiliary base. This concept has been used to synthesise and characterise more then two dozen different bis-guanidines based on 12 discrete monoguanidine units and seven different spacers. These spacers have been chosen such that the most important phenotypes have been dealt with and which range from rigid to more flexible scaffolds. In addition to spacers with no metal-bind-

Keywords: Absolute configuration / Antimicrobial activity / Endophytic fungus / Macrodiolides / Phoma sp. / Pyrenophorol Pyrenophorol (1) and (-)-dihydropyrenophorin (3), two known macrodiolides, were isolated together with four new analogues (2, 4-6) and three ring-opened derivatives (7-9) from Phoma sp., an endophytic fungus isolated from Lycium intricatum from Gomera. The structures of the new compounds were elucidated by detailed spectroscopic analysis, comparison with reported data, and chemical interconversion. The absolute configurations were determined by chemical correlations and a modified Mosher's method. The diversity of these seven newly discovered metabolites not only ex-

The complex [Re 2 (CO) 8 (MeCN) 2 ] 1 reacted with thiols or H 2 S, respectively, by SH oxidative addition in toluene at 80 ЊC to give hydrido sulfido bridged dirhenium complexes of the general formula [Re 2 (µ-H)(µ-SR)(CO) 8 ] (R = H 2a, n-Bu 2b, Cy 2c, Ph 2d, C 6 H 4 F-p 2e, C 6 F 5 2f or 2-naphthyl 2g) in 60 to 80% yield. Complexes 2c and 2g have been characterised by crystal structure analysis. Complex 2a undergoes reaction with another equivalent of 1 to form the novel spirocyclic complex [{Re 2 (µ-H)(CO) 8 } 2 (µ 4 S)] 3. In order to demonstrate the acidity of the µ-H ligand 2g was deprotonated by the base 1,8-diazabicyclo[5.4.0]undec-7-ene to give the anion [Re 2 (µ-S(2-naph))(CO) 8 ] Ϫ 4 Ϫ (naph = naphthyl) which can be isolated as its PPh 4 ϩ salt. This reacts with one equivalent of [MCl(PPh 3 )] (M = Au, Ag or Cu) to give the novel heteronuclear cluster complexes [Re 2 (MPPh 3 )(µ-S(2-naph))(CO) 8 ] (M = Au 5a, Ag 5b or Cu 5c) and PPh 4 Cl. The molecular structures of 5a and 5b have been established by single crystal X-ray analysis.

In THF solution the dirhenium complex Re 2 (µ-H)(µ-PCy 2 )(CO) 8 (1) reacts with an equimolar amount of LiPh at -100°C to afford after warming up to room temperature within 1 h the salt Li[Re 2 (µ-H)(µ-PCy 2 )(C(Ph)O)-(CO) 7 ] (Li[2]). Through cation exchange of Li + against PPh 4 + , Li[2] gives the airstable solid PPh 4 [2] in 86% yield. The selectivity of the LiPh attack at one of the four axial carbonyls in 1 was proved by the chiral shift reagent Eu(hfac) 3 which was dissolved in a CDCl 3 solution of PPh 4 [2]. The 1 H and 31 P NMR spectra show the diastereomeric resolution of the respective peaks in an integral ratio of 1:1 e.g. ∆δ(µ-P) 0.43. The anion [2 -] generates with 2 equiv of XAuPPh 3 (X ) Cl, Br, I) in THF at room temperature within 15 min under release of the leaving group PhCHO the yellow cluster complexes Re 2 (AuPPh 3 ) 2 (µ-PCy 2 )(CO) 7 X (4a-c). Their precursor complex anions [Re 2 (µ-AuPPh 3 )(µ-PCy 2 )(CO) 7 X] -(3a-c) are obtained from 1 and an equimolar amount of XAuPPh 3 or from the deauration by treatment of 4a (X ) Cl) with 1 equiv of LiPh via a transmetalation reaction. Such anions are isolable as salts, N(PPh 3 ) 2 [3a-c]. All new cluster complexes are identified by means of 1 H NMR, 31 P NMR and ν(CO) IR spectroscopic measurements, Li[2] and 4a (X ) Cl) additionally by means of X-ray single-crystal structure analyses. Li[2] crystallizes triclinic, space group P1 h, Z ) 2, a ) 10.536(2) Å, b ) 11.433(2) Å, c ) 19.125(3) Å, R ) 98.01(1)°, ) 89.94(1)°, and γ ) 112.22(1)°; 4a crystallizes monoclinic, space group P2 1 /c, with Z ) 4, a ) 18.615(5) Å, b ) 13.606 (2) Å, c ) 24.223(6) Å, and ) 105.14(2)°. The molecular structure of Li[2] shows a µ-H-, µ-P-bridged Re-Re bond of 3.1667(7) Å, the one of 4a a tetrahedrally shaped Re 2 Au 2 core with a µ-P-bridged Re-Re edge of 3.2680(10) Å.

New massarilactones C (3) and D (4), massarigenin E (5), and coniothyrenol (6) were isolated from Coniothyrium sp. together with the known graphislactone A (1) and massarilactone A (2). The relative configuration of coniothyrenol (6) with an unprecedented benzo[a]xanthene skeleton and ten chirality centers was determined by 1D‐ and 2D‐NMR spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)